Beam construction

ABSTRACT

A construction member which includes an upper chord, a lower chord, a web interconnecting the upper and lower chords, and a plurality of link blocks positioned in stacked relation between the upper and lower chords. The link blocks are joined to each other, to the upper and lower chords, and also to the web. The upper and lower chords, the web and the link blocks may be formed of wood. Grooves may be formed in the upper and lower chords which receive the upper and lower edge portions of the web with the upper and lower edge portions being retained within the grooves through means of an adhesive. A groove may also be formed in the stacked link blocks to receive an end portion of the web with the end portion being retained within the groove through use of an adhesive.

United States Patent 1191 Harmon 1451 Nov. 26, 1974 BEAM CONSTRUCTION [76] Inventor: Harold J. Harmon, 15069 Valley Blvd., Fontana, Calif. 92335 [22] Filed: May 4, 1973 21 Appl. No.: 357,162

[52] US. Cl. 52/729, 52/227 [51] Int. Cl. E04c 3/14 [58] Field of Search 52/729, 227

[56] References Cited UNITED STATES PATENTS 1,377,891 5/1921 Knight 52/729 X 2,230,628 2/1941 Sahlberg 1 52/729 X 2,382,201 8/1945 Burke et a1. .1 .....'52/729 X 2,886,857 5/1959 Brosenius .1 52/729 X FOREIGN PATENTS OR APPLICATIONS 130,818 8/1919 Great Britain 52/729 324,576 11/1957 Switzerland 52/730 Primary ExaminerPrice C. Faw, Jr. Attorney, Agent, or Firm-Thomas 11. Jones [5 7 ABSTRACT A construction member which includes an upper chord, a lower chord, a web interconnecting the upper and lower chords, and a plurality of link blocks positioned in stacked relation between the upper and lower chords. The link blocks are joined to each other, to the upper and lower chords, and also to the web.

The upper and lower chords, the web and the link blocks may be formed of wood. Grooves may be formed in the upper and lower chords which receive the upper and lower edge portions of the web with the upper and lower edge portions being retained within the grooves through means of an adhesive A groove may also be formed in the stacked link blocks to receive an end portion of the web with the end portion being retained within the groove through use of an adhesive.

21 Claims, 5 Drawing; Figures BEAM CONSTRUCTION BACKGROUND OF THE INVENTION With all of the varied construction materials which have been developed by modern science, wood is still the most widely used construction material. Unfortunately, wood is in relatively short supply and will become more so in the years ahead. Thus, it would be de sirable to use the available supply of wood more effectively as a construction material. This would provide greater usage of the available wood supplies by being able to use less wood for given construction jobs and, thereby, being able to hold back timber in reserve for future needs.

Wood members are commonly used in construction as beams and purlins. To increase the strength of the beams or purlins, the wood members may be joined together as a composite structure of a particular configuration having improved strength. It would be desirable to improve the strength of beams or purlins so that structural members of equal strength could be formed from a lesser quantity of wood. As stated, this would provide more efficient use of available lumber and would permit better conservation of timber for future needs.

SUMMARY OF THE INVENTION In accord with the present invention, I have provided an improved structural member which generally is formed of wooden members. By reason of its construction, the structural member of the invention provides greater strength from a given quantity of lumber.

The construction member of the invention, which may be used as a beam or a purlin, includes an upper chord, a lower chord, and a web interconnecting the upper and lower chords. A plurality of link blocks are positioned in stacked relation at the ends of the structural member between the upper and lower chords with the link blocks being joined to each other and also to the upper and lower chords. Additionally, the web is joined to the upper and lower chords and also to the link blocks.

In securing the web to the upper and lower chords and to the link blocks, grooves may be formed in the upper and lower chords and also in the stacked link blocks with the edges of the web being retained within these grooves. An adhesive, such as wood glue, may be placed within the grooves to provide adhesion between the web, the upper and lower chords, and the link blocks.

The web may have a thickness which is substantially less than the width of the upper and lower chords. The web may then be positioned along the axis ofthe upper and lower chords with the link blocks having a width which is substantially the same as the width of the upper and lower chords.

The web, which is preferably formed of plywood,.

may be formed from a single board or may be formed in a sandwich construction in which a plurality of web members are positioned substantially parallel to each other with a filler material positioned between adjacent web members.

In addition to end link blocks being placed at the ends of the construction member, intermediate link blocks may be provided at intermediate locations along the length ofthe construction member. Preferably. the distance between the link blocks as measured along the length of the construction member is in the order of about 6 to about 8 feet. Also, the number of link blocks positioned in a stacked relation between the upper and lower chords generally numbers about three or more and most preferably about five or more.

Intermediate link blocks may be joined at opposite surfaces to the web through grooves formed in the opposite surfaces which receive an end portion of the web. An adhesive placed within the grooves may then firmly secure the intermediate link blocks to the web. The web is discontinuous at the location of the intermediate link blocks and, thus, the intermediate link blocks serve as a bridge in firmly joining the separate web portions together. Also, the intermediate link blocks securely join the web to the upper and lower chords.

If desired, the bond between link blocks which are positioned in stacked relation between the upper and lower chords may be provided in whole or in part by bearing plates positioned on the outer surfaces of the upper and lower chords over the location of the link blocks. Tie members may then be utilized which extend through aligned apertures in the bearing plates, the upper and lower chords and in the link blocks. On tightening of the tie members, a compressive force may then be exerted through the bearing plates on the upper and lower chords and the stacked link blocks placed therebetween.

In the use of tie members, the tie members may be substantially positioned on the center line of the upper and lower chords. Preferably, the distance between the centers of the tie members is sufficiently large so as not to weaken the structural member, e.g., a distance be tween centers of at least about one and onehalf inches or greater.

In the use of grooves in the upper and lower chords and in the stacked link blocks for retention of the web with respect to the chords and link. blocks, the grooves preferably have a given depth with respect to the width of the web. Preferably, the depth of the groove or grooves in the stacked link blocks which retain an end portion of the web is in the order of about three times the thickness of the web. The grooves in the upper and lower chords which retain the upper and lower edge portions of the web preferably have a depth in the order of about two times the thickness of the web.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing, which is merely illustrative of an embodiment of the invention,

FIG. 1 is a broken perspective view ofa construction member in which an upper chord and a lower chord are interconnected by a web with a stacked plurality of link blocks being positioned at the ends of the construction member and also at an intermediate location;

FIG. 2 is a sectional view of the construction member taken along the line 2-2 of FIG. I and illustrating the connection between the web and the stack of link blocks positioned at one of the ends of the construction member;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. I and illustrating the connection between the web and the stack of link blocks positioned at an. intermediate location on the construction member;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3 to illustrate the connection between a stack of link blocks and a web formed of a single board, and

FIG. 5 is a sectional view, similar to FIG..4, illustrating the connection between a stack of link blocks and a web having a sandwich construction.

DETAILED DESCRIPTION A construction member 2, shown in FIG. 1, includes an upper chord 4, and a lower chord 6, and a web 8 joining the upper and lower chords. As illustrated in the broken portion of FIG. 1, the cross-sectional configuration of the construction member 2 resembles that of an I-beam in which the upper and lower chords 4 and 6 form the legs of the I while the web 8 forms the interconnection between the two legs.

A plurality of end link blocks 10 are positioned in a stack at either end of the construction member 2 with the end link blocks being secured to each other, to the upper chord 4 and lower chord 6, and also to the web 8. The presence of the link blocks 10 and their connection to the upper and lower chords 4 and 6 and to the web 8 has been found to materially strengthen the construction member 2. Although not bound by any theory, it is believed that the principal function of the link blocks 10 in providing increased strength involves the interconnection between the link blocks and the web 8 through which the web is stiffened and is better able to provide support to the upper and lower chords 4 and 6.

Depending upon the length ofthe construction member 2, stacks of intermediate link blocks 12 may be positioned at intervals along the length of the construction member. Preferably, the distance between the trated in FIG. 1, are joined to each other and also to the upper chord 4 and lower chord 6 in the same manner as the end link blocks 10. Additionally, however, the intermediate link blocks 12 are joined at opposite faces to the web 8, with the web being discontinuous at the location of the intermediate link blocks.

The end link blocks 10 and intermediate link blocks 12 may be joined to each other and also to the upper chord 4 and lower chord 6 by any convenient means, such as the use of bearing plates 16 which are positioned on the outer surfaces of the upper chord 4 and lower chord 6 in alignment with the link blocks witli tie members 14 extending through the bearing plates, upper and lower chords and through the stacked link blocks.

FIG. 2, which is a sectional view taken along the line I 22 of FIG. I, illustrates the connection of the end link blocks 10 with each other and also with the upper chord 4, the lower chord 6, and the web 8. The construction member 2 is generally formed of wooden members with the web 8 preferably being formed of plywood or a material of similar strength. The upper chord 4 may, for example, be formed from two upper chord members 18 while three lower chord members may be utilized in forming the lower chord 6.

Wood is stronger in compression than in tension. Thus, assuming that the loading of the construction member would be applied to the upper chord 4, the upper chord may be made from only two chord members 18 to carry the compressive loading in the upper chord. However, the lower chord 6, which is in tension,

may be made heavier and stronger through use of three lower chord members 20. The number of members used in forming the upper and lower chords 4 and 6 may, ofcourse, be varied depending upon the size and thickness of the individual chord members and the design strength of the construction member 2. If desired, the upper chord members 18 may be joined to each other along a glue line 19 and the lower chord members 20 may be joined to each other along glue lines 21.

An upper groove 22 may be formed on the underside of the upper chord 4 to engage the upper edge of the web 8 while a lower groove 24 may be formed on the inner side of the lower chord 6 to engage the lower edge of the web. The upper and lower edge portions of the web 8 may be secured within the upper groove 22 and lower groove 24 by means of an adhesive, such as wood glue. The end edge portion of the web 8 may engage an end groove 26 formed on the inner faces of the stack of end link blocks 10. The depth of the end groove 26 is illustrated by the distance between the end surface 28 of the web 8 with respect to the end surfaces 30 of the link blocks 10.

As stated, the'end link blocks 10 are secured to each other and also to the upper chord 4 and the lower chord 6. This is illustrated by the glue lines denoted 32 between the individual link blocks 10 and the glue lines 34 between the end link blocks of the stack and the upper and lower chords 4 and 6. Preferably, the number of link blocks 10 which are stacked between the upper and lower chords 4 and 6 is three or more and most preferably each stack contains five or more link blocks. The strength of the bond at the glue lines 32 and 34 will generally exceed the strength of the material forming the link blocks 10. Thus, the bonding provided along the glue lines 32 and 34 will generally be sufficient to secure the link blocks 10 to each other and to the upper and lower chords 4 and 6.

If desired, additional bonding may be provided between the link blocks 10 and the upper and lower chords 4 and 6 by the tie members 14 extending through the bearing plates 16 and aligned apertures in the upper and lower chords and the link blocks. The tie members 14 may include head portions 36 which bear against one of the plates 16 and with nuts 38 or other similar means which threadedly engage the tie members and bear against the other plate 16. By threading the nuts 38 onto the tie members 14, a compressive force is exerted on the link blocks 10 and the upper and lower chords 4 and 6 through the bearing plates 16.

The structural relationship of the intermediate link blocks 12 with respect to the upper and lower chords 4 and 6 and the web 8 is illustrated in FIG. 3 which is a sectional view taken along the line 3-3 of FIG. I. As illustrated, the web 8 is discontinuous at the location of the intermediate link blocks I2 which are positioned in a stacked relationship between the lower surface of the upper chord 4 and the upper or inner surface of the lower chord 6. The web 8, as shown at the left of FIG. 3, has an end portion which is received in an intermediate groove 40 formed in the surfaces of the stacked link blocks 12. The depth of the groove 40 is illustrated by the distance between the web end 41 and the ends 42 of the link blocks 12. The web 8, as shown at the right of FIG. 3, has an end portion which is received in an intermediate groove 44 formed in the link blocks 12 with the depth of the groove 44 being illustrated by the distance betweenthe link block ends 46 and the web end 45.

As in the case of the end link blocks 10, the intermediate link blocks 12 may be secured to each other along glue lines 48 and the upper and lower link blocks in the stack may be secured respectively to the upper and lower chords 4 and 6 through the glue lines 50. Also, the link blocks 12 may be placed in compression through the use of tie members 14 and bearing plates 16 as described previously.

As illustrated, the intermediate link blocks 12 provide additional strength for the construction member 2 by forming a very strong bridge between the ends 41 and 45 of the web 8. The separated ends 41 and 45 of the web 8 may be firmly secured within the intermediate grooves 40 and 44 through the use of a suitable adhesive such as a wood glue which contacts not only the ends of the web, but also the side surfaces of the web in contact with the surfaces of the intermediate grooves.

FIG. 4, which is a sectional view taken along the line 4-4 of FIG. 3, illustrates the connection between the intermediate link blocks 12 andthe web 8. As shown, the end portion of the web 8 may be retained within the intermediate groove 40 by an adhesive bond along side glue lines 52 and an end glue line 54. Also, the bottom edge of the web 8 may be retained within the lower groove 24 by means .of an adhesive bond along the bottom glue lines 56. A hole 58 in the intermediate link blocks I2 may receive one of the tie members 14 as described previously.

It has been observed that the strength of the bond between the link blocks and the web is of great importance to the function of the link blocks in providing strength for the structural member 2. The bond be tween the intermediate link block 12 and the web 8, as shown in FIG. 4, is primarily through the bonding to the side surfaces of the web as indicated by the side glue lines 52. The strength of this bonding will generally exceed the strength of the material forming the link blocks 12 or the web 8.

Preferably, the web 8 is constructed of plywood or a material of similar strength and the depth of the grooves in the link blocks, e.g., grooves 40, 44 or 26, is preferably in the order ofabout three times the thickness of the web. The depth of the upper and lower grooves 22 and 24 through which the web 8 is secured to the upper and lower chords 4 and 6 is preferably in the order of about twice the thickness of the web.

FIG. 5 illustrates a further embodiment of the invention in which the web has a sandwich construction with a plurality of web members 63 having a filler material 65, such as polystyrene foam, interposed between the adjacent web members. Each of the web members 63 may be separately retained within a groove 64 formed in link blocks 60 and each web member may be separately retained in a bottom groove 70 formed in a bottom chord member 62. The web members 63 may be retained within the grooves 64 through use of an adhesive placedalong the side glue lines 66 and the end glue lines 68.

By using a plurality of web members, such as the web members 63, the bonding area provided between the web members and the link blocks 60 may be increased in direct proportion to the number of web members. For example, there are four side glue lines 66 in the use of two web members 63, as shown in FIG. 5, but only two side glue lines 52 for a single web 8 as shown in FIG. 4. By increasing the number of web members, the bonding area between the web and the link blocks may be increased without increasing the depth of the groove in the link blocks within which the web is retained. This is advantageous since it avoids the possible introduction of structural weakness into the structural member L by too great an increase in the depth of the groove in the link blocks.

Similarly, through use of a plurality of web members 63, the bonding area between the web members and the upper and lower chords 4 and 6 may be increased in direct proportion to the number of web members. For example, with twoweb membersfl63, there are four bottom glue lines 72 while with a single web 8 there are, as shown in FIG. 4, only two bottom glue lines 56. Thus, the bonding area between the web and the upper and lower chords 4 and 6 may be increased by using a plurality of web members without increasing the depth of the grooves in the chords within which the web members are retained. This is advantageous since it provides increased bonding without the possible introduction of structural weakness into the chords 4 and 6 by an increase in the depth of the: grooves 22 and 24.

I claim:

1. A construction member comprising:

an upper chord;

a lower chord;

a web interconnecting the upper and lower chords;

a plurality of link blocks positioned in stacked relation between the upper and lower chords at the ends of said chords;

said link blocks each having a depth which is substantially less than the distance between the upper and lower chords;

said web having a length which is less than the length of said upper and lower chords;

said link blocks in each stack of link blocks being joined to each other and each stack of link blocks being joined to said upper and lower chords;

said web having ends, and

each of said ends being joined to a plurality of link blocks,

whereby the stack of link blocks at each of the ends of the chords fixes the position of the ends of the upper and lower chords and also the position of the web with respect to the upper and lower chords in securing the chords and the web together as a construction member. I

2. The construction member of claim 1 wherein:

the upper and lower chords each having substantially the same width,

the web has a thickness which is substantially less than the width of the upper and lower chords with the web being generally positioned along the axis of the upper and lower chords, and

the link blocks have a width which is substantially the same as the width of the upper and lower chords.

3. The construction member of claim 2 including:

' an upper groove in said upper chord with an upper edge portion of the web being retained in the upper groove;

a lower groove in said lower chord with a lower edge portion of the web being retained in the lower groove;

- an end groove in the stacked link blocks positioned at each of the ends of said chords, and

an end edge portion of the web being retained in each of said end grooves.

4. The construction member of claim 2 including:

a bearing plate positioned on the outer surface of the upper chord at each of its ends above a stack of link blocks;

a bearing plate positioned on the outer surface of the lower chord at each of its ends below a stack of link blocks, and

a plurality of tie members extending through said bearing plates, the upper and lower chords and said link blocks with said tie members exerting a compressive force on said link blocks through said bearing plates.

5. The construction member of claim 4 wherein:

said tie members are positioned substantially on the axis of the upper and lower chords.

6. The construction member of claim 1 including:

an upper groove in said upper chord with an upper edge portion of the web being retained in the upper groove;

a lower groove in said lower chord with a lower edge portion of the web being retained in the lower groove;

and end groove in the stacked link blocks positioned at each of the ends of said chords, and

an end edge portion of the web being retained in each of said end grooves.

7. The construction member of claim 6 wherein:

the upper chord, the lower chord, the web and the link blocks are constructed of wood, and

the web is secured in place within the upper groove,

the lower groove, and the end groove by an adhesive.

8. The construction member of claim 7 wherein:

the stacked link blocks are secured to each other and to the upper and lower chords by an adhesive.

9. The construction member of claim 1 wherein the upper chord, the lower chord, the web and the link blocks are constructed of wood.

10. The construction member of claim 9 wherein the web has a sandwich construction in which a plurality of web members are positioned substantially parallel to each other with a filler material positioned between adjacent web members.

11. The construction member of claim 10 including:

upper grooves in the upper chord for each of the web members with an upper edge portion of each web member being retained in an upper groove;

lower grooves in the lower chord for each of the web members with a lower edge portion of each web member being retained in a lower groove, and

end grooves in each of the stacks of link blocks for each of the web members with an end edge portion of each web member being retained in an end groove.

12. The construction member of claim 11 wherein:

each web member is secured in place within an upper groove, 21 lower groove, and an end groove by an adhesive.

13. The construction member of claim 12 wherein:

the stacked link blocks are secured to each other and to the upper and lower chords by an adhesive.

14. The construction member of claim 1 wherein each stack of link blocks contains three or more link blocks.

15. The construction member of claim 1 wherein each stack of link blocks contains five or more link blocks.

16. A construction member comprising:

an upper chord;

a lower chord;

a web interconnecting the upper and lower chords;

a plurality of end link blocks positioned in stacked relation at either end of said construction member with the end link blocks having inner sides joined to said web;

a plurality of intermediate link blocks positioned in stacked relation at an intermediate position on the construction member with-the intermediate link blocks being joined at one side to the web and being joined at an opposite side to the web;

said web being discontinuous at the location of the intermediate link blocks;

the link blocks in each stack of link blocks being joined to each other, and

each stack of link blocks being joined to said upper and lower chords.

17. The construction member of claim 16 wherein the upper chord, the lower chord, the web and the link blocks are constructed of wood;

theweb is joined to the upper and lower chords and the stacked link blocks through glued joints, and

the link blocks are glued to each other and to the upper and lower chords.

18. The construction member of claim 17 wherein the distance between the locations of the stacked link blocks along the length of the construction member is in the order of about six to about eight feet.

19. The construction member of claim 18 wherein the web is constructed of plywood of a given thickness;

the glued joints between the web and the upper and lower chords have a depth which is about twice the thickness of the web, and

the glued joints between the ends of the web and the stacked link blocks have a depth which is about three times the thickness of the web.

20. The construction member of claim 16 wherein each stack of link blocks contains three or more link blocks.

21. The construction member of claim 16 wherein each stack of link blocks contains five or more link blocks. 

1. A construction member comprising: an upper chord; a lower chord; a web interconnecting the upper and lower chords; a plurality of link blocks positioned in stacked relation between the upper and lower chords at the ends of said chords; said link blocks each having a depth which is substantially less than the distance between the upper and lower chords; said web having a length which is less than the length of said upper and lower chords; said link blocks in each stack of link blocks being joined to each other and each stack of link blocks being joined to said upper and lower chords; said web having ends, and each of said ends being joined to a plurality of link blocks, whereby the stack of link blocks at each of the ends of the chords fixes the position of the ends of the upper and lower chords and also the position of the web with respect to the upper and lower chords in securing the chords and the web together as a construction member.
 2. The construction member of claim 1 wherein: the upper and lower chords each having substantially the same width, the web has a thickness which is substantially less than the width of the upper and lower chords with the web being generally positioned along the axis of the upper and lower chords, and the link blocks have a width which is substantially the same as the width of the upper and lower chords.
 3. The construction member of claim 2 including: an upper groove in said upper chord with an upper edge portion of the web being retained in the upper groove; a lower groove in said lower chord with a lower edge portion of the web being retained in the lower groove; an end groove in the stacked link blocks positioned at each of the ends of said chords, and an end edge portion of the web being retained in each of said end grooves.
 4. The construction member of claim 2 including: a bearing plate positioned on the outer surface of the upper chord at each of its ends above a stack of link blocks; a bearing plate positioned on the outer surface of the lower chord at each of its ends below a stack of link blocks, and a plurality of tie members extending through said bearing plates, the upper and lower chords and said link blocks with said tie members exerting a compressive force on said link blocks through said bearing plates.
 5. The construction member of claim 4 wherein: said tie members are positioned substantially on the axis of the upper and lower chords.
 6. The construction member of claim 1 including: an upper groove in said upper chord with an upper edge portion of the web being retained in the upper groove; a lower groove in said lower chord with a lower edge portion of the web being retained in the lower groove; an end groove in the stacked link blocks positioned at each of the ends of said chords, and an end edge portion of the web being retained in each of said end grooves.
 7. The construction member of claim 6 wherein: the upper chord, the lower chord, the web and the link blocks are constructed of wood, and the web is secured in place within the upper groove, the lower groove, and the end groove by an adhesive.
 8. The construction member of claim 7 wherein: the stacked link blocks are secured to each other and to the upper and lower chords by an adhesive.
 9. The construction member of claim 1 wherein the upper chord, the lower chord, the web and the link blocks are constructed of wood.
 10. The construction member of claim 9 wherein the web has a sandwich construction in which a plurality of web members are positioned substantially parallel to each other with a filler material positioned between adjacent web members.
 11. The construction member of claim 10 including: upper grooves in the upper chord for each of the web members with an upper edge portion of each web member being retained in an upper groove; lower grooves in the lower chord for each of the web members with a lower edge portion of each web member being retained in a lower groove, and end grooves in each of the stacks of link blocks for each of the web members with an end edge portion of each web member being retained in an end groove.
 12. The construction member of claim 11 wherein: each web member is secured in place within an upper groove, a lower groove, and an end groove by an adhesive.
 13. The construction member of claim 12 wherein: the stacked link blocks are secured to each other and to the upper and lower chords by an adhesive.
 14. The construction member of claim 1 wherein each stack of link blocks contains three or more link blocks.
 15. The construction member of claim 1 wherein each stack of lInk blocks contains five or more link blocks.
 16. A construction member comprising: an upper chord; a lower chord; a web interconnecting the upper and lower chords; a plurality of end link blocks positioned in stacked relation at either end of said construction member with the end link blocks having inner sides joined to said web; a plurality of intermediate link blocks positioned in stacked relation at an intermediate position on the construction member with the intermediate link blocks being joined at one side to the web and being joined at an opposite side to the web; said web being discontinuous at the location of the intermediate link blocks; the link blocks in each stack of link blocks being joined to each other, and each stack of link blocks being joined to said upper and lower chords.
 17. The construction member of claim 16 wherein the upper chord, the lower chord, the web and the link blocks are constructed of wood; the web is joined to the upper and lower chords and the stacked link blocks through glued joints, and the link blocks are glued to each other and to the upper and lower chords.
 18. The construction member of claim 17 wherein the distance between the locations of the stacked link blocks along the length of the construction member is in the order of about six to about eight feet.
 19. The construction member of claim 18 wherein the web is constructed of plywood of a given thickness; the glued joints between the web and the upper and lower chords have a depth which is about twice the thickness of the web, and the glued joints between the ends of the web and the stacked link blocks have a depth which is about three times the thickness of the web.
 20. The construction member of claim 16 wherein each stack of link blocks contains three or more link blocks.
 21. The construction member of claim 16 wherein each stack of link blocks contains five or more link blocks. 